Register for 2025 USNCO Exams
2025 USNCO Student Registration is closed.
For more information, contact your ACS Local Section USNCO Coordinator.
Exam Information
Understand the exam format
Local Exams Format
Multiple Choice
110 min | 60 multiple-choice questions
Covers broad chemistry topics
National Exams Format
Part I: Problem Solving
90 min | 60 multiple-choice questions
Covers broad chemistry topics
Part II: Problem Solving
105 min | 8 written questions
Covers chemical theories and models
Part III: Lab Practical
90 min | 2 laboratory practicals
Involves problem solving in the laboratory
Multiple Choice Topics
Multiple choice USNCO (both local and national) exams cover the following topics:
| Questions | Topic |
|---|---|
| 1 – 6 | Stoichiometry/Solutions |
| 7 – 12 | Descriptive/Laboratory |
| 13 – 18 | States of Matter |
| 19 – 24 | Thermodynamics |
| 25 – 30 | Kinetics |
| 31 – 36 | Equilibrium |
| 37 – 42 | Oxidation - Reduction |
| 43 – 48 | Atomic Structure/Periodicity |
| 49 – 54 | Bonding/Molecular Structure |
| 55 – 60 | Organic/Biochemistry |
Number of Nominees
More than 1,000 students sit for the three-part National Exam each April. Coordinators nominate students for the National Exam based on the results of the Local Competitions. Each Local Section can nominate only a certain number of students determined by the number of its ACS members. No more than two students from any given school can compete in the National Exam.
See the allowed numbers of nominees below or downoad a PDF of the allotment of nominees by ACS Local Section.
| ACS Members | USNCO Nominees |
|---|---|
| 1–1000 | 12 |
| 1001-1350 | 13 |
| 1351-1700 | 14 |
| 1701-2050 | 16 |
| 2051-2400 | 17 |
| 2401-2750 | 18 |
| 2751-3100 | 19 |
| 3101-3450 | 20 |
| 3451-3800 | 22 |
| 3801-4150 | 23 |
| ACS Members | USNCO Nominees |
|---|---|
| 4151-4500 | 24 |
| 4501-4850 | 25 |
| 4851-5200 | 26 |
| 5201-5550 | 28 |
| 5551-5900 | 29 |
| 5901-6250 | 30 |
| 6251-6600 | 31 |
| 6601-6950 | 32 |
| 6951-7300 | 34 |
| 7301-7650 | 35 |
Students during the Chemistry Olympiad laboratory work
Scoring
ACS calculates the average number of correctly answered questions by topic area. Based on this average, each student's score in a particular topic is compared to the overall average and rated as: Below Average, Average, Above Average, or Outstanding Performance.
Only student scores for Part I (multiple-choice) are sent to the Local Section coordinators to be distributed to students.
Results
The 20 top-scoring students are invited to attend a study camp to compete for a spot in the U.S. team. Based on the score of their overall performance, some students are recognized with High Honors and Honors and receive a certificate from the USNCO national office. Approximately the top 50 students are recognized as High Honors and the next 100 as Honors. The list of High Honor and Honor students is published on the USNCO website.
Learn about the exam format and how to prepare for exams.
